The primary objectives of a firearm magazine are to: (1) store ammunition; (2) supply ammunition to the firing chamber; and (3) provide a means to reload the magazine with additional ammunition. The magazine should be as relatively small for a given amount of ammunition so that it will not interfere with operation of the firearm. It should also be light weight, rugged in construction, and low in cost. When the magazine is used in each of the three modes (storing, feeding, and reloading), a minimum of effort to convert from one mode to another mode is also desirable.
Many current gun magazines have a duct like body holding the ammunition or bullets, a base plate attached to one end of the body opposite the firearm interface, and a feeding spring in contact with the bottom-most plate. Many magazines include a follower at the spring/ammunition interface to assist compression load distribution and feeding or stripping of the ammunition to the firing chamber.
Most of the current firearm magazines may operate well in one of these modes, but in other modes, very poorly. In the first mode, the objective is to store as many rounds of ammunition as possible in a given space. This space may be inside the firearm handle, in replaceable canisters or clips, or within certain envelope limitations. The storage container should protect the ammunition from adverse environmental impacts. Springs, followers and walls for impact protection can reduce available space for storage.
The second mode requires a mechanism to move the ammunition towards the firing chamber and sequentially force rounds to the top of the magazine to be stripped off by the bolt. This is typically accomplished with a relatively stiff feeding spring (i.e.: a high spring constant which, when compressed, can apply large loads on the ammunition to force it to the top of the magazine. If rapid firing is desired, spring force may require further modification.
The final mode of operation, reloading may be accomplished while the magazine is attached to the firearm on some firearms. More commonly, reloading is accomplished with the magazine detached from the firearm. A large manual effort is normally required to compress the stiff spring within the magazine. A special loading tool is sometimes used. This manual effort is particularly difficult if the user is chilled, fatigued or tense.
In many cases, the manual reloading force is greater than can be exerted by a significant portion of the users, preclude manual loading by these users. Even if the user is capable of the manual effort required, the task may result in injury or at least sore, tired fingers and pain unless carefully accomplished, especially when many magazines are to be loaded. Another problem may occur when a magazine is taken apart for cleaning, typically by sliding off the base plate. The spring can shoot out, injuring the user. The most common approach to some of these problem is the use of a tool or reloading device. Magazine reloading tools and devices tend to be complex and cumbersome. Some loading tools are very simple, but they take time to attach and use and must work against full spring pressure. They may also limit convenient transport, access and use of the firearm.
In another approach to achieve good multi-mode performance, a telescoping magazine is employed. This allows a portion of the magazine to be extended during reloading, relieving some or all of the force in the spring. This allows reloading without some or all of the compression required. Once loaded, the telescoping magazine is then collapsed, re-applying spring force to feed ammunition to the firing chamber. Examples of telescoping magazines are illustrated in U.S. Pat. Nos. 1,044,983 and 4,472,900.
Other approaches, sometimes in conjunction with telescoping magazines, are the use of various spring guides, stops or notches as part of the duct-like magazine body. These provide lateral support for the spring during compression or expansion, and may prevent the spring from erratic motions during reloading or feeding thus jamming the magazine or firearm. One example is illustrated in U.S. Pat. No. 3,726,038.
Still another approach has been to use adjustable springs. These can vary the spring forces during reloading and feeding. They can be used in fixed or telescoping magazines. Examples of adjustable spring magazines are illustrated in U.S. Pat. Nos. 3,964,199 and 3,443,334.
No prior art spring biased magazine the applicant is aware of allows manual storage or reloading without some spring compression force. Telescoping magazines minimize this compression (most of the compression is typically accomplished during closing telescopic motions), but does not eliminate it.
What is needed is a biasing or spring device which can repeatedly supply force to feed the ammunition to the firing chamber, without the need for complex guides or magazine protrusions, requires minimal storage space, prevents spring from loss and shooting out during cleaning and requires little or no significant spring compression force during reloading, thus speeding manual reloading and precluding the need for special loading tools.